Ellipsoidal compass



March 31, 1953 KAFKA 2,632,953

ELLIPSOIDAL COMPASS Filed Feb. 11, 1950 IN VEN TOR. ROBERT S. KAFKAATTORNEY Patented Mar. 31, 1953 UNITED STATES PATENT OFFICE ELLIPSOIDALCOMPASS Robert s. Kafka, Woodside, N. Y.

Application February 11, 1950, Serial No. 143,639

3 Claims.

This invention relates to an ellipsoidal compass.

It is an object of the invention to make a compass that will drawellipses. Another object is to make a compass that will draw ellipses ofdiner-entratios of longitudinal to transverse axis, being of infiniteadjustability from aperfect circle to an ellipse of very large axialratio.

The objects of the invention are accomplished, generally speaking, by anellipsoidal compass having legs connected by a frame pivotally androtatably mounted on one leg and pivotally and slidably mounted on theother leg.

The above and further objects and novel features of the presentinvention will more fully appear from the following detailed descriptionwhen th same is read in connection with the accompanying drawings. It isto be expressly understood, however, that the drawings are for thepurpose of llustration only and are not in tended as a definition of thelimits of the invention, reference for this latter purpose being badprimarily to the appended claims.

In the drawings, wherein like reference characters refer to like partsthroughout the several views:

Figure 1 is a side elevational view of an ellipsoidal compass;

Figure 2 is a section on line 2-2 of Figure 1;

Figure 3 is a section on line 3-3 of Figure 2;

Figure 4 is a plan view of a modified form of the invention, partly insection; and,

Figure 5 is a section through Figure 4 on line 5-5.

In the figures, the numeral l4 indicates the center leg of the compass0, the term center leg indicating the leg which serves as a pivot aboutwhich the other turns. This leg is provided at the end with a needle 11and at the top with a fixed grip 13. The leg is oifset at l4-I5 and theoffset portion is formed in the shape of a ball bearing 44, the centerof which is on the axis of the leg and of pin H. The upper portion 12 ofthe center leg constitutes a shaft which serves to support a block IIwhich is slidably mounted thereon. A coil spring 48 bears at its endagainst the top of block H and the bottom of grip l3. The sides of theblock I l are flattend above and below ledges 54, the part below thisledge being reduced by the width of a frame or guide is which is ofU-shape and firmly and rigidly connected at its ends 2! to the revolvingleg 22 of the compass. The block H has a snug but sliding fit betweenthe arms of the U-shaped guide 18, which is connected to the portions ofthe block H above the ledge 54 by parallel motion means,

2 which are shown in this instance as four straps I9 pivoted at theirupper ends to the block and at their lower ends to the frame by pivotpins 28.

By this construction, the center leg may move up and down through theblock ll against the pressure of the spring 48, an upper limit of motion being established by a. limit stop on the upper end of part M- ofthe leg, and back and forth parallel to the revolvable leg as permittedby the parallel motion of the straps l9.

Rigidly fixed at the ends of the U-shaped frame I3 is the revolving leg22 which is provided with a guide 24, extending along the inner sidethereof, formed by slots in opposite sides of the leg; The leg has twoparts, the outer and longer of which, 23, is pivoted to that portionwhich is firmly affixed to the frame 18, enabling the draftsman toadjust the position of his lead without altering the basic setting ofinstrument. This outer part holds lead 28 in the usual grip 27.

A frame 32-33 is pivotally and slidably mounted on the guide by means ofslider 29. slider has a, socket 3 9 which receives a ball 3| on theframe part 32. The sides of the socket 30 are extended far enough tobear upon the shank that connects the ball to the frame, leaving a slotthat is parallel to the leg and permitting the slider to move along theguide 24 without cramping, but preventing side play.

The frame part 32 is a yoke slidably mounted between the plates 33-34 ofthe frame part 33. The lateral tension upon the yoke may be varied by aslider 45 and a cam pressure member 46, eliminating all side play as theplates 33, 34 eliminate all vertical play. The member 33 (or 34) hasblocks that engage the sides of the yoke and permit it to move only in astraight and unwavering line. The yoke may be manually moved betweenplates 33-34 and retains its position after being moved.

A block 39 is immovably fixed between the plates 33-34 and is providedwith a bearing opening that snugly engages a bearing sleeve 35. beingrevolvable about the sleeve and held from motion along it by the pressedon bushing 35 and The sleeve is provided with cut away parts whichpermit it to tilt about a pivot pin 40 fixedly mounted in a ballbearing44 formed in the part of leg it between offsets I4-l5. A setscrew 4| prevents the pin 49 from moving freely.

By this means the frame may be placed at right angles or at an acuteangle to the axis of the center leg. The offset parts i4-l5 engagediagonally opposed parts of the sleeve 36 as an abutment when the frame3233 is at right angles to the leg. The position of the two legs withrespect to each other can be altered by moving the yoke through thegripping plates, without changing the character of the curve that willbe drawn by the instrument, but only its size. The shape of the ellipseis altered by altering the angular relation of the frame to the centerleg, by tilting about pivot 49.

The operation of the instrumentis based upon the observation that theprojection of a circle which is at an acute angle to the axis ofprojection is an ellipse. Thus, if one takes a coin and looks squarelyat it, it appears circular, but if it be tilted somewhat about adiameter it loses its circular appearance and becomes elliptical. Thisinstrument makes use of that prim ciple. The sleeve 36 on the ball 43 isa circle about which bearing 39 in the connection 3 can revolve. Thesleeve can tilt about the pin 40, and the frame tilts withit. Whenviewed from above in position normal to the axis ofthe leg itsprojection is circular, but when tilted its projection is an ellipse andany object which compelled to follow the, circumference of the sleeve 35will travel in an elliptical path corresponding to the. projection anddirectly related to the angle between the axis ofthe socket and the axisoi the center leg. By adjusting the yoke 32-33 between the plates aseries of ellipses can be drawn concentrically and in parallel,differing in size alone. By adjusting the plane of the connection 32-33with respect to the axis of the center leg the shape of the ellipse isaltered. When the connecting frame is normal to the center leg thecompass draws a true circle. When the angle is altered slightly thefigure departs slightly from the circularposition, becoming slightlyelliptical. ihe figure drawn becomes increasingly elliptical as theangle of the frame to the center leg increases. The center legautomatically adjusts itself to the proper length for cooperation withthe revolving leg, a worthwhile advantage.

In Figures 4 and 5, the center leg BI is screw threaded at 65. A nut 62is screwed up to the limit of the thread and this nut is provided withrecessed, diametricall positioned, half bearings in which the pins 10 ofa ring 56 are seated. A washer 63 having opposed half bearings isengaged with the pin '10 and a nut Eli is screwed on the thread 55 andholds the parts in position. The ring is cut awe-3 to pcrnnt it to hetilted about the pins Hi. A circular frame or annulus 6'! is held aboutthe ring it by upper and lower plates B869. The frame 61, 68, 69 canthus turn around the ring 65 and may be connected to the revolvable legof the compass byv bearing 3| which fits the slider 29 as hereinabovedescribed.

As many apparently widely diiferent embodiments of the present inventionmay be made without departing from the spirit and scope thereof, it isto be understood that the invention is not limited to the specificembodiments.

What is claimed is:

1. An ellipsoidal compass having a center leg and a single revolvingleg, parallel motion means connecting the revolving leg the center leg,said means comprising two parallel links having pivotal axesperpendicular to the plane ontaining the longitudinal axes of said legs,a slider movable along the revolving leg and having a ball socketslotted parallel to the center leg, a frame having a ball connectionwith said socket and a shank guided by the slot, a circular bearingtiltably mounted on a pivot on and normal to the axis of the center leg,and a circular bearing on theframel'engaging the said first-mentionedcircular bearing, permitting angular adjustment of the frame on thecenter leg.

2. An ellipsoidal compass having a center leg and a. single revolvingleg, guide means rigidly connected to said revolving leg and movabletransversely relative to said center leg, parallel motion meansconnecting the revolving leg to the center leg, said parallel motionmeans comprising two parallel links pivotally mounted on said center legand said guide means, the pivotal axes of said links being perpendicularto the plane containing the longitudinal axes of said legs, a slidermovable along the revolving leg and having a ball socket slottedparallel to the center leg, a frame having a ball connection with saidsocket and a shank engaged by the sides of the slot, and a ring tiltablymounted on the center leg, said frame having slidable and rotatableconnection with said ring and said revolving leg being rotatable withthe frame.

3. A11 ellipsoidal compass having a center. leg and a single revolvingleg, guide means rigidly connected to said revolving leg and movabletransversely relative to said center leg, parallel motion meansconnecting the revolving leg to the center leg, said parallel motionmeans compris ing two parallel links pivotally mounted on said centerleg and said guide means, the pivotal axes of said links beingperpendicular to the plane containing the longitudinal axes of saidlegs, a slider movable along the revolving leg and having a ball socketslotted parallel to the center leg, a frame having a call connectionwith said socket and a shank guided by the slot, 2. circular bearingtiltably mounted on a pivot normal to the center leg, a circular bearingon the frame engaging the said circular bearing, permitting angularadjustment of the frame on the leg, said revolving leg being comprisedof a part connected to the slider and a pivoted part having means tosupport writing means.

ROBERT s. KAFKA.

REFERENCES CITED The following references are of record in the fileofthis patent:

STATES PATENTS Number. Name Date 715,883 Sherman T Dec. 16, 1905 1,406,33 Hoffman et al. Feb. 14, 1922 2,493,229 Dibrell Jan. 3, 1950 FOREIGNPATENTS Number Country Date 70,680 Germany Aug. 31, 1893 M3266 AustriaOct. 25, 1935 325,095 Germany Sept. 10, 1920 136,830 Great Britain Oct.18, 1935

